This invention relates to dual voltage battery systems, and more particularly to an electric switch by which to enable selection between such dual voltage outputs and also to maintain the batteries in parallel for charging from a conventional charging voltage source.
Dual voltage electrical systems are finding increased applications. Typical of these is the use of a 12/24 volt electric trolling motor, as in bass boats, wherein the boat is also provided with an internal combustion engine as the main drive source, the engine having a 12 volt electrical system and a 12 volt engine-driven alternator or generator.
Heretofore, such a dual voltage electrical system utilized one of the batteries only for the 12 volt demand, and both batteries connected together in series for the 24 volt demand. Since the 12 volt demand battery delivers more ampere-hours than the other battery of the pair, the batteries require different charging rates. However, this cannot be accommodated with the batteries connected in series, since one battery would overcharge and the other would undercharge.
Accordingly, it has been the practice heretofore to disconnect the batteries from their series arrangement and reconnect them for parallel charging by a conventional 12 volt charging source. This is a time consuming procedure, and a particularly annoying one to fishermen who have tired from the strenuous activities of the fishing day. Moreover, since such reconnections often must be made under poor lighting conditions prevailing at dockside, inadvertent errors may result in electrical shorting or arcing that can cause explosion of or other damage to the batteries. A series-parallel arranged toggle switch has been utilized for manual switching in an attempt to overcome the problems associated with the reconnection procedure discussed hereinbefore. However, such a switch results in violation of basic battery charging principles and thus is unsatisfactory.